Biomonitoring measurements in blood, urine, and other tissues are crucial for studies to understand the effects of environmental chemicals on health. Participants almost always want to learn their own results, and modern ethics statements support their right-to-know. In response, more studies are returning personal results for growing numbers of chemicals, even if health effects are uncertain. Research to evaluate the outcomes in these studies shows that report-back encourages recruitment and retention, leads researchers to new translational insights about their data, and increases environmental health literacy for participants (EHL, the ability to understand and act on knowledge to protect health). Participants do not become overly worried. Thus, new tools to scale up production of personalized reports benefit both researchers and study participants. The Digital Exposure Report-Back Interface (DERBI) is a tested software framework for efficiently producing reports for print, computer/tablet, or smartphone. However, two barriers limit its scalability and usability. First, it currently requires researchers to have advanced programming skills, which most teams lack. Second, smartphone reports are needed for low-income communities where phone is the primary access to the internet, and the beta smartphone version requires additional development. This methods-development project addresses these gaps by expanding both the researcher- and study-participant functionality of DERBI. Aim 1 will increase access to report-back by building an easy-to-use dashboard (interface), so any researcher can use DERBI to visualize personal data and create reports without programming skills. Five NIEHS-supported teams ? each composed of a researcher and a community partner -- will provide input to design the dashboard and then user-test it with their own data, which includes measurements of polycyclic aromatic hydrocarbons, environmental phenols, and highly fluorinated substances (PFAS), among others. Researchers will be able to visualize their data to gain insights and tailor reports to their study population. Aim 2 will develop, field, and evaluate smartphone reports as a tool for growing environmental health literacy among cohort participants. Smartphone DERBI has been deployed in beta version in just one study, PROTECT in Puerto Rico. This project will use feedback from PROTECT and user-test a new tutorial feature to engage curiosity and support lower-EHL users in reading their results. We will user-test and deploy the improved smartphone report in Chemicals in Our Bodies, a diverse pregnancy cohort in the San Francisco area. Using quantitative pre- and post-tests, we will assess participant learning, emotional response, and exposure-related behavior. This project will create and actively disseminate a free software package for any researcher to generate high-quality, biomonitoring reports on smartphone, using methods that support environmental health literacy in vulnerable communities. By developing communications about chemical exposures, it will immediately advance translation of exposure science to improve public health.